Bobbin thread case opener mechanism



J ly 4, 19 1 s. J. KETTERER 2,990,794

BOBBIN THREAD CASE OPENER MECHANISM Filed April 6, 1959 2 Sheets-Sheet 1 INVEN 4 Stanley J. Ke'r r ATTORNEY S. J. KETTERER BOBBIN THREAD CASE OPENER MECHANISM July 4, 1961 2 SheetsSheet 2 Filed April 6, 1959 Fig.2.

Fig.3.

INVENTOR. Stanley 9 J. Ketterer BY ATTORZWY WITNESS Unimd Sums Patent r 2,990,794 BOBBIN THREAD CASE OPENER MECHANISM Stanley J. Ketterer, Stratford, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed Apr. 6, 1959, Ser. No. 804,470 3 Claims. (Cl. 112-228) novel and improved bobbin thread case opener mechanism for a lock stitch sewing machine.

Another object of this invention is the provision of a bobbin thread case opener mechanism constructed and arranged to admit passage of the needle thread loop past the bobbin thread case rotation restraining means during those intervals of each stitch forming cycle when the needle thread loop is subjected to the least stress from other sources.

More particularly, it is an object of this invention to provide an improved bobbin thread case opening mechanism which will admit a needle thread loop past the bobbin thread rotation restraining means during the period of gradual take up of the needle thread loop from the loop taker and not during loop seizure and rapid expansion of the loop by the loop taker.

With the above and other objects and advantages in view, as 'will hereinafter appear, this invention comprises the devices, combinations, and arrangement of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a front elevational view of a lock stitch sewing machine loop taker having a bobbin thread case opener mechanism of this invention applied thereto and including portions of the sewing machine frame as well as the needle and a needle thread,

FIG. 2 represents a top plan view of the loop taker of FIG. 1 with a portion of the sewing machine frame illustrated in horizontal cross section,

FIG. 3 is a vertical cross-sectional view taken substantially along line 3-3 of FIG. 1,

FIG. 4is an enlarged front elevational view of the bobbin thread case opener mechanism including a fragment of the bobbin thread case, with the rotation restraining member illustrated in cross section taken substantially along line 44 of FIG. 2 and with the actuating cam illustrated in vertical cross section in the extreme position illustrated in FIG. 1,

FIG. 5 is a view similar to FIG. 4, but with the actuating cam and the bobbin thread case opener parts illustrated in the opposite extreme position,

FIG. *6 is a top plan view of the loop taker and the bobbin thread case rotation restraining member in the position of parts illustrated in FIG. 4, and

FIG. 7 is a view similar to FIG. 6, but with the mechanism in the position of parts illustrated in FIG. 5.

In conventional lock stitch sewing instrumentalities with which the present invention is adapted for use, a rotary loop taker cooperates with the needle to draw out a loop of needle thread and to carry the needle thread loop about a mass of thread stored on a bobbin within the loop taker.

One obstacle to the free passage of the needle thread loop about the bobbin is the means which suports the bobbin within the loop taker. A common expedient in the "art to provide for passage of the thread loop past the means supporting the bobbin is that of fitting the bobbin 2,990,794 Patented July 4, 1961 within a bobbin case. The bobbin case preferably comprises a bobbin case base such as is indicated at 11 in FIG. 3, which base is formed with a bearing rib 12 journaled in a raceway 13 formed in the loop taker 1-4. The loop taker is formed with a cylindrical shank 15 disposed coaxially and in driven relation with a hook drive shaft 16 in the machine frame -17. A loop seizing beak 18 formed on the loop taker serves to engage and draw out a loop of needle thread. By providing a gap 19 in the bearing rib 1-2 and a gap 20 in the loop taker raceway 13, and by preventing the base 11 from rotating with the loop taker so that the gaps 19 and 20 periodically overlap, it will be appreciated that the needle thread loop can enter between the base and the loop taker when the gaps 19 and 20 overlap, and after being drawn completely about the bobbin, the needle thread loop may be withdrawn from between the base and the loop taker when the gaps 19 and 20 again overlap.

The bobbin case is also provided with a bobbin case cover 21 which can serve many purposes such as that of latching the bobbin in place on the base 11, that of providing a smooth snag-free outer shell over which the needle thread loop can pass, and that of supporting bobbin thread tensioning means. The cover 21 and the base 11 together thus provide a bobbin case which, because of the frictional drag of the bearing rib 12 in the raceway 13 of the rotating loop taker, will be forced tightly against the usual means serving to restrain the bobbin case from rotation.

The bobbin case rotation restraining means is thus another obstacle to the free passage of the needle thread loop about the bobbin, and presents a serious problem particularly in high speed sewing machines wherein the frictional forces between the raceway and the bearing rib increase in magnitude and the stresses imposed on the needle thread from other sources increase to the point where the thread could be broken if it were simply to be pulled past the rotation restraining means.

This invention pertains to a novel and improved bobbin c'ase rotation restraining means which is actuated in timed relation with the loop taker automatically to open a passage for the needle thread loop, such mechanism being referred to in the art as bobbin case opener mechanism.

As best illustrated in FIGS. 4, 5, 6 and 7, the bobbin case base 11 is formed with two radial projections 30 and 31 space-d angularly about the periphery of the bobbin case base. The projection 30 is comparatively squat and tapers smoothly into the periphery of the bobbin case base at the side opposite the projection 31. On that side facing the projection 31, the projection 30 is formed with an abutment surface 32. The projection 31 extends radially outward-1y from the periphery of the bobbin case base farther than the projection 30. The side of the projection 31 which is opposite the projection 30 is formed radially outwardly with respect to the abutment surface 32 with a slabbed abutment portion 33.

Cooperating with the projections 30 and 31 of the bobbin case base is an arched rotation restraining arm 35 formed with a laterally extending stop member 36 disposed to work between the projections 30 and 31 and to cooperate with the abutment surface 32. The rotation restraining arm 35 is also formed with a laterally extending stop member 37 disposed to Work adjacent to the projection 31 and to cooperate with the abutment surface 33. The rotation restraining arm 35 is formed integral with a bracket 38 which embraces a bearing pin 39 secured by a set screw 40 in the machine frame. The bracket is also formed with a sector slot 41 which accommodates a clamp screw 42 threaded into an oscillating cam follower member 43 which is journaled on the bearing pin 39. The cam follower is formed with a bifurcated arm 44 embracing a three- 3 cornered cam 45 fast on the shank 15 of the loop taker. With this construction, the rotation restraining arm 35 is oscillated one complete cycle for each rotation of the loop taker with a considerable dwell occurring at each extreme position of oscillation.

As illustrated in FIG. 1, the stop members 36 and 37 of the rotation restraining arm 35 are arranged substantially equidistant from the rotary axis of the loop taker and are disposed so as to restrain the projections 30 and 31 of the bobbin case base and the abutment surfaces 32 and 33 thereon on that side of the path of reciprocation of endwise reciprocatory needle 50 from which the beak 18 of the loop taker moves in engaging a needle thread loop.

By means of the clamp screw 42 and the sector slot 41, the rotation restraining arm may be adjusted such that the extreme positions of oscillation occur as illustrated in FIGS. 4 and 5. In the extreme position shown in FIG. 4, the rotation restraining stop member 36 is disposed in engagement with the abutment surface 32 on the bobbin case base and the stop member 37 of the rotation restraining arm is disposed out of engagement with the abutment surface 33 and in spaced relation to the projection 31 thus providing a passageway therebetween for the needle thread loop. In the other extreme position of the rotation restraining arm as shown in FIG. 5, the stop member 37 of the rotation restraining arm engages the abutment surface 33 of the projection 31 while the stop member 36 is out of engagement with the abutment surface 32 and completely free of the bobbin case base thus providing a passageway for escape of a needle thread loop therefrom.

Illustrated in FIG. 1 is the needle thread loop which has been engaged by the loop taker beak moving in clockwise direction. The parts are shown in FIG. 1 in the position in which the needle thread loop is almost completely expanded about the bobbin case by the loop taker. From the point of initial contact of the needle thread loop by the loop taker to the position as illustrated in FIG. 1 wherein the loop taker ceases to draw out the needle thread loop, the loop taker has traveled only half a revolution. Since the loop taker rotates twice for each needle reciprocation, the needle thread loop is drawn out into the position illustrated in FIG. 1 in approximately one quarter of the needle reciprocating cycle. During this period of rapid needle thread loop enlargement by the loop taker, the thread in the present invention is not subjected to any additional stresses incident to passage past the bobbin rotation restraining means. As illustrated in FIG. 1, the bobbin case base projections 30 and 31 are restrained entirely on that side of the path of the needle reciprocation from which the loop taker moves to engage the needle thread loop. Until the needle thread loop has been completely enlarged by the loop taker, the thread is not influenced by the bobbin case opener mechanism of this invention.

In FIGS. 1, 6 and 7, that limb of the needle thread loop which enters the raceway and bearing rib gaps and passes in back of the bobbin case between the bobbin case base and the loop taker is indicated as B while that limb of the thread loop which is cast across the front of the bobbin case and must, therefore, pass through the bobbin case opener is indicated as F.

FIG. 6 is a top plan view of the loop taker and bobbin case opener mechanism in the same position of parts illustrated in FIG. 1. The bobbin case opener cam 45 is preferably timed to shift the rotation restraining arm 35 into an extreme position nearest to the axis of the loop taker and to provide for a dwell of the arm 35 in this extreme position as the needle thread loop is expanded to encompass the bobbin case. The stop member 36 in this position is disposed in engagement with the abutment surface 32 on the bobbin case base while the stop member 37 occupies a position out of engagement with the abutment surface 33 and'spaced from the projection 31 on the bobbin case base. As the limb F of the needle thread loop is drawn across the face of the bobbin case by the action of the loop taker and thereafter by the sewing machine take up (not shown), it will enter the space between the stop member 37 and the projection 31 as soon as the thread limb F becomes aligned therewith.

As the loop taker continues to rotate for approximately one half revolution beyond the position illustrated in FIG. 1, the needle thread loop will be drawn up by the sewing machine take up to the extent that the needle thread loop will leave the loop taker and not be caught by the loop taker beak in its idle rotation. As the beak of the loop taker traverses the path of reciprocation of the needle to begin the idle rotation of the loop taker, the needle thread loop will be disposed substantially as illustrated in FIG. 7. The bobbin case opener parts in this position are further illustrated in FIG. 5.

The bobbin case opener cam 45 having turned one half revolution with the loop taker will have shifted the rotation restraining arm 35 into an extreme outer position in which the stop member 37 contacts the abutment surfaces 33 of the projection 31, while the stop member 36 is shifted completely free of the abutment surface 32 on the bobbin case base. The needle thread limb F being drawn up by the sewing machine take up is free therefore to pass through the opening between the stop member 36 and the bobbin case base to free the needle thread loop from the bobbin case rotation restraining means.

Since the limb B of the needle thread loop will be released from the loop taker raceway and the bearing rib of the bobbin case when the gaps therein overlap, the needle thread loop is thus completely free of the loop taker mechanism and may be drawn up into the work to set the stitch.

The abutment surfaces 32 and 33 on the bobbin case base projections 30 and 31 are disposed in mutually parallel relation and preferably formed as arcs having radii centered coincident with the axis of the bearing pin 39 which supports the rotation restraining arm 35. The projection 30, moreover, is preferably dimensioned with respect to the abutment surface 33 such that the stop member 37 engages the abutment 33 before the stop member 36 is free of the abutment surface 32 on the outward movement of the rotation restraining arm 35. The stop members 36 and 37 thus alternately prevent rotation of the bobbin case, and the transition from one to the other is accomplished smoothly and Without occasioning any oscillatory motion of the bobbin case. The operation of this bobbin case opener mechanism will thus be smooth and quiet and, therefore, will be suited for use with high speed sewing machines.

Having thus described the nature of the invention, what I claim herein is:

1. A bobbin case opener mechanism for a lock stitch sewing machine having an endwise reciprocatory threaded needle, a thread carrying bobbin, a rotary loop taker, and a bobbin case journaled in said loop taker, said bobbin case opener mechanism comprising, means projecting radially from one side of said bobbin case and formed with a pair of abutment surfaces disposed in mutually parallel spaced relation, a pair of movable stops disposed on that side of the path of needle reciprocation from which the loop taker moves in engaging a needle thread loop, said movable stops cooperating each with one of said pair of abutment surfaces to prevent rotation of said bobbin case with said loop taker, each one of said pair of abutment surfaces being offset relatively to said cooperating pair of movable stops at different distances from the axis of rotation of said loop taker, and means for vibrating said movable stops in unison toward and away from the axis of rotation of said loop taker to position said movable stops alternately in engagement with their cooperating abutment surfaces for passage of a needle thread loop in seriatim therebetween.

'2. A bobbin case opener mechanism for a lock stitch sewing machine having an endwise reciprocatory threaded needle, a thread carrying bobbin, a rotary loop taker, and a bobbin case journaled in said loop taker, said bobbin case opener mechanism comprising means projecting radially from one side of said bobbin case and formed with a pair of abutment surfaces disposed in mutually parallel spaced relation, a movable rotation restraining arm, a pair of stop surfaces formed on said arm and disposed on that side of the path of needle reciprocation from which the loop taker moves in engaging a needle thread loop, said movable stop surfaces spaced apart a distance equal to the space between said abutment surfaces and cooperating each with one of said pair of abutment surfaces to prevent rotation of said bobbin case with said loop taker, each one of said pair of abutment surfaces being offset relatively to said cooperating pair of stop surfaces at different distances from the axis of rotation of said loop taker, means pivotally supporting said rotation restraining arm at one side of said loop taker, and cam means associated with said loop taker and rotating at the same speed thereof for oscillating said rotation restraining arm toward and away from the axis of rotation of said loop taker to position said movable stop surfaces alternately in engagement with their cooperating abutment surfaces for passage of a needle thread loop in seriatim therebetween.

3. A bobbin case opener mechanism for a lock stitch sewing machine having an endwise reciprocating threaded needle, a thread carrying bobbin, a rotary loop taker formed with a loop seizing beak and a bobbin case journaled in said loop taker, said bobbin case opener mechanism comprising, a pair of substantially radial projections formed on said bobbin case in angularly spaced relation about the periphery thereof, an abutment surface formed on each of said projections, said abutment surfaces disposed equidistant from each other and at different distances from the axis of rotation of the loop taker, a rotation restraining arm pivotally supported on an axis parallel to the rotary axis of said loop taker, a pair of stop members carried by said rotation restraining arm substantially equidistant from the rotary axis of said loop taker and disposed on that side of the path of needle reciprocation from which the loop taker moves in engaging a needle thread loop, said pair of stop members cooperating each with one of said abutment surfaces to prevent rotation of said bobbin case with said loop taker, and means for oscillating said rotation restraining member toward and away from the rotary axis of said loop taker one oscillation for each rotation of said loop taker to position said stop members alternately in engagement with their cooperating abutment surfaces for passage of a needle thread loop in seriatim therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 1,995,278 Kessler Mar. 19, 1935 2,138,939 Pudelko Dec. 6, 1938 2,452,756 Hohmann Nov. 2, 1948 2,543,475 Slodysko Feb. 27, 1951 

